Microtome and electrostatic dispersal apparatus therefor



June 2i,1949- H. R. JOHNSON 2,473,753

MICROTOME AND ELECTROSTATIC DISPERSAL APPARATUS THEREFOR Filed Nov. 20, 1946 Patented June 21, 1949 UNITED "S TATES .MICROTOME AND ELECTRQSTATICiDE- :PERSAL APPARATUS THEREFQB jHowai-d" R" J hnson,'Baltim0re, Md.

Application November 20,1946, serialrNmflli l -w (Cl; as -40) 6 Claims.

Thisinventlonrelatestto improvements in electrostatic dispersal units;

An .objectofuthe invention is to provide an improved electrostatic dispersal unit. for use in connectioniwith-microtomes.for setting up an alternating magnetic fieldabout a specimen holder and a cutter which will 'createan eddy current in the specimenholder and cutter so that-the charges on the. cutter will tend to neutralizethe charges on the specimen and the specimen may be cut in a more precise manner thanwashere tofore possible.

Another object of .theinvention is to provide an improved electrostaticdispersal unit for microtomes and any other specimen cutting apparatus including means for setting up an alternating magnetic field between the specimen holder and cutter which will create an eddy current in the holder and cutter, and means including a 1'0- tatable rollformed of Bakelite or any other de sired insulating material which will be slowly revolved by a suitable driving means connected to the microtome operating mechanism, whereby the thin specimens as they are sliced from the object will-be-fed in chain form over said roller to a suitable collecting receptacle.

A'iurther object of'the invention is to provide animproved mechanism for use with a microtome for neutralizing the static charges between a cutter and specimen, said mechanism including means for setting up an eddy current field about the specimen'object holder and cutter, a paper envelope disposable over the entire cutter except that portion of the cutter that actually cuts the specimens, "and an insulated driven roller for feeding or discharging'the specimens in chain form after being cut, to be received and collected in perfect condition, without appreciable static charges, in a suitable collecting container or receptacle' from which the specimen will be removed and madeup into microscopic slides.

Another object of the invention is to provide an improved-electrostatic dispersal unit for microtomes which will be-highly efiicient in operation,

and relatively inexpensive tomanufacture and produce.

Other objects will appear as the description proceeds.

vIn the accompanying drawings'which form a part of this application,

Figure'l is a side elevation of a microtome with Figure2 is a plan'view of a microtome being partly broken away to show the improved electro- F '2 static. dispersal limit and step=down transformer with. circuit connections incorporated therein;

Figure ,3. isa.Iper s'pective view of the specimen object l holder lwith a c coil surrounding. the shank portion of tthesame'iorsettingup aneddy current field about said holder;

Figure .4 is a perspective-viewiofctheespecimen cuttingx knife .bladel'showing. the paper insulation envelope surrounding the same, and

Figured is a vertlcalsectionalview through the holder with specimen object supported I thereon and thecutting knife. intheprocess of slicing off a specimen "for useinmakingmicroscope slides.

,Like characters ,ofrreferenceare .used throughout thefollowing specification-and the accompanying drawings to designate corresponding parts.

' In carryingout the invention, there is provided a microtome of.a wel1;'kno wn. construction generally indicated: by .thereference numeral l.

The microtome l'is .provide'd with the usual operating pulleywheel. o drive wheel 2 .on which a han'dle't is secured 'or th :wheel 2 which is provided with a 'per-ipheral-groovefli may be driven bya beltandplectric. motor (not shown) in the event that 1 a "considerable amount .of sectioning has to -be done.

-- substantially V'-sha-ped :in across section. The

shank '8 of .-.the: specimen holder -is formed with opposed" flatlsidesllat itsirmer en'd for supporting 1 the .rholder 21in athe :rectpnocating 1 object holder clamp l0.

.AfTCQil ill s-of-srelectriclwire is .wound about the intermediate :i-shank wportion of the specimen holder and is connected in series with-the sec- ,ondary winding :12 ,1 of 1a step downi transformer generally.desi natedibyc the. reference numeral I 3, which hasxa-gprimary :winding [4 .adapted to be connected :by. meansvofnthe:electric conductor 15 with anyssuitablezsourcemfizelectric :current. supply (not shown) wherebyi' whenithe ,coil I l is energized, an eddy current field will be set up around thespecimen holder andthecuttingarea adjacent l-thereto.

A specimen block IE or mixers-other desired material having the specimen tissue embedded therein will be forced against the roughened outer face of the head 6 and will be firmly supported thereon.

An adjustable knife blade or cutter IT is supported in position adjacent the specimen holding head 6, whereby when the microtome I is operated, a specimen block [5 will be fed forwardly after each specimen has been cut, prior to the downward movement of the holder head 6 to cause the specimen block to engage and move downwardly over the fixed cutting knife blade ll to effect the cutting off of the specimens.

An elongated paper envelope I8 is provided for completely surrounding and encasing the knife blade H, the same being open at one edge adjacent the cutting edge of the knife blade I1, and the sides of the envelope are cut out as at H! centrally of its length to permit the unrestricted operation of the cutting blade knife as it is engaged by the specimen block 16. The envelope 18 serves as an insulating medium for the blade I! tending to prevent conductive contact between the cutter H and the cutter holding clamp l8 of the microtome I.

A guide roller 20 of Bakelite or any other desired insulating material is mounted on the shaft 2! which extends between the bearings 22 and 23 on the base of the microtome I, and extends in parallel relation to the cutting blade [1. A pulley 24 is secured to one end of the shaft 2|, and is connected by the belt 25 with a second pulley 26 on the shaft 21 connected with and driven by the microtome driving or operating mechanism.

In operation, the step-down transformer I3 is connected with any suitable source of electric current supply (not shown), and the specimen block I6 is secured to the face of the holder head 6. The microtome I is then set into operation, and the specimens will be sliced from the specimen block l6, each specimen 28 as it is cut engaging the adjacent edge of the preceding specimen, thereby forming a chain which will be fed over the insulated guide roller 20 relatively free of any static electricity charge which would cause the specimens to bunch together, thereby producing imperfect sections which are difficult to remove for observation, and which, due to the static charges thereon, will prevent satisfactory obser- 0 vation of the specimens when under a microscope.

The chain of specimens 28 will be fed to any suitable container or receptacle from which they may be removed as desired and made into microscopic slides.

It has been found that when means for dispersing electrosatic charges from the area around the specimen and its cutting area are not provided, imperfect specimens will be sectioned. However, when an electrostatic dispersal unit is used similar to that forming the subject matter of the instant invention, perfect specimens or specimens free from static charges will be sectioned and perfect microscopic slides will be made possible.

While the preferred embodiment of the instant invention has been illustrated and described, it will be understood that it is not intended to limit the scope of the invention thereto, as many minor changes in detail of construction may be resorted to without departure from the spirit of the invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination with a microtome including a cutter as a part thereof, means carried by the microtome for holding a specimen relative to the cutter to be cut by the latter, and means supported on the microtome setting up an alternating magnetic field about the holding means and cutter, and for creating an eddy current in the holding means and cutter.

2. The combination of claim 1 wherein said second mentioned means includes a coil carried by the holding means and connected to a source of electric current, said coil being so positioned to envelop the holding means and cutter in a pulsating magnetic field, said holding means and said cutter being relatively reciprocable.

3. In combination with a microtome including a cutter, means for holding a specimen relative to the cutter to be sliced by the latter, a coil carried by the holding means and connected to a source of electric current for setting up an alternating magnetic field about the holding means and cutter and setting up an eddy current in the holding means and cutter, said cutter including a cutting edge, and means for insulating the cutter, the cutting edge of said cutter being exposed from the insulating means.

4. In combination with a microtome including a cutter and a cutter clamp, means for holding a specimen relative to the cutter to be sliced by the latter, a coil carried by the holding means and connected to a source of electric current for setting up an alternating magnetic field about the holding means and cutter and setting up an eddy current in the holding means and cutter, said cutter including a cutting edge, and a flexible covering of insulating material carried by and substantially covering the surface of the cutter, the cutting edge of said cutter being exposed from the insulated covering, said covering insulating I said cutter from its clamp and said holding means including a head portion having projecting ribs for receiving a specimen block.

5. In combination with a microtome including a cutter and a driving member, means for holding a specimen relative to the cutter to be engaged by the latter, means carried by the microtome setting up an alternating magnetic field about the holding means and the cutter and for setting up an eddy current in the holdin means and cutter, and an insulated conveyor operatively connected to the driving member of said microtome and disposed adjacent the cutter for guiding specimens in chain form as the same are cut by the cutter.

6. In combination with a microtome including a cutter, a driving member, means for holding a specimen relative to the cutter to be engaged by the latter, a coil carried by the holding means and connected to a source of electric current, said coil being so positioned to envelop the holding means and cutter in a pulsating magnetic field, and for setting up an eddy current in the holding means and cutter, said cutter including a cutting edge, an insulating coverin for the cutter, the cutting edge of said cutter being exposed from the insulating covering, and an insulated guide roller carried by the microtome adjacent the cutter and operatively connected to the driving member of the microtome for guiding specimens in chain form as the same are cut by the cutter, said holding means and said cutter being relatively reciprocable.

HOWARD R. JOHNSON.

(References on following page) 6 Name Date Chapman July 9, 1940 Richards Aug. 11, 1942 FOREIGN PATENTS Country Date Great Britain (1900) Nov. 2, 1901 OTHER REFERENCES "Static Electricity, Circular C438, National Bureau of Standards (1942), especially pages 9, 

